The invention relates to compositions and methods for decontamination of materials, particularly to decontamination of materials contaminated with isocyanates.
The materials of components of equipment used in manufacture of flexible urethane foam, rigid urethane foam, RIM urethane foam and the like can become fouled with isocyanate. These materials must be treated to minimize the possibility of the isocyanate reacting with moisture in the air to form undesirable polyurea solids on the surfaces of the components.
It is desirable to prevent formation of polyurea solids by removing isocyanates from these materials before the isocyanates react with moisture. Although polyurea solids can be removed from components by mechanical action after a lengthy soak in a strong agent such as N-methyl pyrrolidone, this is not practical. Moreover, this is not desirable due to the strong solvency of N-methyl pyrrolidone which destroys rubber components such as seals and hoses.
A known method for treating a material contaminated with isocyanate is to treat the material with methylene chloride. Methylene chloride, however, has a high xe2x80x9cOzone Depletion Potentialxe2x80x9d.
Other known methods for treating isocyanate contaminated material include flushing the material with agents such as dioctyl phthalate, DBE, i.e., blends of dibasic esters of dimethyl succinate, glutarate, and adipate. Dioctyl phthalate and DBE, however, each have viscosities greater than 50 centipoise and permit reaction of water with MDI to generate excessive polyurea residue.
Various cleaning solvents such as propylene carbonate also have been used to decontaminate isocyanate fouled materials. Once the propylene carbonate cleaning solvent becomes contaminated with isocyanate, however, disposal of the contaminated solvent becomes difficult and expensive due to presence of unreacted isocyanate.
A need therefore exists for compositions and methods for removal of isocyanates from isocyanate fouled material which overcomes problems such as those described above.
The invention relates to a composition for treating materials fouled with isocyanate. The composition includes an alkylene carbonate and a primary hydroxyl functional capping agent. The alkylene carbonate may be any of propylene carbonate and ethylene carbonate, preferably propylene carbonate. More preferably, the alkylene carbonate is propylene carbonate such as ARCONATE(copyright) HP propylene carbonate having a purity of about 99.7%, a pH of about 6.5-7.5, and a solubility in water of about 1-10%. The primary hydroxyl capping agent may be any of methoxypolyoxyethylene monol, polyoxyethylene-polyoxypropylene monol, and mixtures thereof, preferably methoxypolyoxyethylene monol, most preferably a methoxypolyoxyethylene monol of the formula CH3xe2x80x94(OCH2CH2)nxe2x80x94OH where n has an average number of 7 such as CARBOWAX(copyright) 350 MPEG. These compositions may further include an alcohol started polyoxyethylene-polyoxypropylene monol, preferably alcohol started polyoxyethylene-polyoxypropylene monol having equal amounts by weight of oxyethylene and oxypropylene groups and a molecular weight of from about 270-3930.
The compositions comprising an alkylene carbonate and a primary hydroxyl functional capping agent may further include a co-solvent such as methanol, propanol, butanol, pentanol, and hexanol.
In another aspect, the invention relates to a method for decontamination of a material fouled with isocyanate. The method entails treating the material with a solvent blend to extract isocyanate for a time sufficient to extract substantially all of the isocyanate from the material being treated into the solvent blend. The solvent blend includes an alkylene carbonate and a primary OH functional capping agent in an amount sufficient to react with substantially all of the isocyanate extracted into the solvent blend. Preferably, the alkylene carbonate is any of propylene carbonate and ethylene carbonate, more preferably propylene carbonate, most preferably propylene carbonate such as ARCONATE(copyright) HP propylene carbonate having a purity of about 99.7%, a pH of about 6.5-7.5, and a solubility in water of about 1-10%. In these solvent blends, the primary hydroxyl capping agent is any of methoxypolyoxyethylene monol, polyoxyethylene-polyoxypropylene monol, and mixtures thereof, preferably methoxypolyoxyethylene monol. The solvent blend may also include a alcohol started polyoxyethylene-polyoxypropylene monol, preferably an alcohol started polyoxyethylene-polyoxypropylene monol having equal amounts by weight of oxyethylene and oxypropylene groups and a molecular weight of about 270-3930.
In yet another aspect, the invention relates to a method for decontamination of a solvent fouled with isocyanate. The method entails blending a solvent with an amount of a primary hydroxyl functional capping agent sufficient to react with substantially all of the isocyanate in the solvent. The solvent is an alkylene carbonate such as propylene carbonate and ethylene carbonate, preferably propylene carbonate, more preferably a propylene carbonate such as ARCONATE(copyright) HP propylene carbonate having a purity of about 99.7%, a pH of about 6.5-7.5, and has a solubility in water of about 1-10%. The primary hydroxyl capping agent is any of methoxypolyoxyethylene monol, polyoxyethylene-polyoxypropylene monol, and mixtures thereof, preferably methoxypolyoxyethylene monol. The blend may also include an alcohol started polyoxyethylene-polyoxypropylene monol, preferably an alcohol started polyoxyethylene-polyoxypropylene monol having equal amounts by weight of oxyethylene and oxypropylene groups and a molecular weight of from about 270-3930.